US 12,255,633 B2
Filter using transversely-excited film bulk acoustic resonators
Luke Myers, Santa Barbara, CA (US); Wei Yang, Goleta, CA (US); Andrew Guyette, San Mateo, CA (US); and Greg Dyer, Santa Barbara, CA (US)
Assigned to MURATA MANUFACTURING CO., LTD., Nagaokakyo (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Apr. 17, 2022, as Appl. No. 17/722,344.
Claims priority of provisional application 63/175,933, filed on Apr. 16, 2021.
Prior Publication US 2022/0337224 A1, Oct. 20, 2022
Int. Cl. H03H 9/60 (2006.01); H03H 9/13 (2006.01); H03H 9/205 (2006.01)
CPC H03H 9/605 (2013.01) [H03H 9/13 (2013.01); H03H 9/205 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A bandpass filter comprising:
a ladder filter circuit comprising two or more shunt transversely-excited film bulk acoustic resonators (XBARs) and two or more series XBARs,
wherein the two or more shunt XBARs and the two or more series XBARs each comprise a diaphragm comprising a lithium niobate (LN) piezoelectric plate,
wherein the diaphragm of each of the two or more shunt XBARs has an LN-equivalent thickness greater than or equal to 360 nm, and the diaphragm of each of the two or more series XBARs has a diaphragm having an LN-equivalent thickness less than or equal to 375 nm,
wherein the at least one series XBAR of the two or more series XBAR comprises a dielectric layer with a thickness of tfsd on the diaphragm, and
wherein the LN-equivalent thickness of the at least one series resonator is teqa=tp+ka(tfsd), where teqa is the LN-equivalent thickness of the at least one series resonator, tp is a thickness of the LN piezoelectric plate of the at least one series resonator, and ka is a proportionality constant that equals approximately 0.52.